wheat vernalization and small grain project report · wheat does not flower as soon as a...
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Wheat vernalization and small grain project report
Reagan NolandExtension Agronomist
West Region Virtual Wheat Tour – May 7, 2020
Winter wheat requires a “chilling” period in order for timely and uniform reproductive growth to occur.
Temperatures need to be between 32 and 45 F.
Temperatures below freezing do not count!
Requirement generally ranges 3 to 6 weeks (500 to 1000 hours) for varieties grown in Texas.
Chilling hour accumulation starts as soon as the seed imbibes with water (before it sprouts).
What is vernalization?
Wheat does NOT flower as soon as a vernalization requirement is met.
Most of our varieties are also photoperiod sensitive.
As days get longer, reproductive growth occurs faster.
Vernalization requirement and maturity are often correlated, but one does not necessarily cause the other.
Timing of maturity also depends on photoperiod sensitivity of the variety.
When does wheat flower?
Sparse or inconsistent head emergenceReduced head size Inconsistent rates of maturity within the fieldThe entire crop may remain vegetative.
Impacts of poor vernalization
Much wheat was planted late Some wheat did not emerge until late December or early January Winter was warmer than normal
2019-2020 Situation
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Aug Sep Oct Nov Dec Jan
Aver
age
Tem
pera
ture
(°F)
Prec
iptia
tion
(in)
30-yr Average Precipitation Precipitation (2019-2020)30-yr Average Temperature Average Temp (2019-2020)
We can forecast vernalization issues based on cumulative chilling hours to date Can get a head-start on contingency plans.
Forecasting Issues
Germination Date
Cumulative chilling hours
Actual Projected
Feb - 7 Mar - 1 Apr - 1
10/15/2019 726 844 918
11/1/2019 647 765 839
11/15/2019 549 667 741
12/1/2019 460 578 652
12/15/2019 360 478 552
1/1/2020 247 365 439
Used variety testing data from multiple sites across the state in 2016-2017 (a bad vernalization year).
Assessing variety differences
SitePlanting
date
Cumulative chilling hours since planting
Yield (bu/ac)
Ending Feb-7
Ending Apr-1
TAM 114
SY Grit SY FlintWB
4515Gallagher
SY Razor
TAM 401
Wharton 11/17/2016 174 183 0.4 0.3 0.7 2.9 5.3 6.6 22.4
College Station 11/3/2016 195 215 4.5 9.5 9 9.2 13 - 17
Uvalde 11/28/2016 211 239 22 6.9 22.1 19.4 54.3 38 41.6
McGregor 11/21/2016 312 396 2.9 13.2 12.1 17.6 24.2 - 18.6
Brady 10/25/2016 403 486 41.4 20.6 29.1 20.4 39.4 27.3 23.3
Abilene 10/27/2016 552 707 46.6 45.5 39.7 32.8 39.5 43.9 35.7
TAM 114 and SY Grit appear to require greater vernalization (~500 hours)
Note that low vernalization requirements generally align with earlier maturity and greater potential risk of frost injury after jointing
Varieties should not be selected based on vernalization requirements alone.
Rather, it is helpful to know the vernalization requirement of the varieties you have planted so that issues can be forecasted in the event of a warm winter.
Variety selection
Depending on how fast you can identify a potential vernalization issue, there is opportunity to:
◉ Avoid potential wasted top-dress fertilizer.
◉ Terminate and get ready for a summer crop.
◉ Graze out (goat prices are good).
Management Implications
Species and Variety Selection
Project reports: Forage variety trial
varietytesting.tamu.edu
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500
1000
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Jan 25 Feb 25 Apr 17
Yiel
d (lb
s/ac
)
Harvest Date
Forage Yield Distribution
TAMbar 501 TAM 114 Trical 348
When do you need the forage?
Grazing & Grain 2019 project assessed seeding rate and cutting height
Dual-use Wheat
Cutting Height vs. Forage Yield
0200400600800
100012001400160018002000
1.75 2.5 3.5 4
Fora
ge Y
ield
(lbs
/acr
e)
Cutting Height (in)
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C
Cutting Height vs. Grain Yield
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Gra
in Y
ield
(bu/
acre
)
Cutting Height (in)
C
BC
ABA
B B A A
05
1015202530
5 6.4 8.9 10.2
CP (%
)
A B B B
01020304050
5 6.4 8.9 10.2
ND
F (%
)
Impact of cutting height on forage nutritive value
A B BC C
010203040
5 6.4 8.9 10.2
ADF
(%)
Cutting Height (cm)
B A A A
0255075
100125150175
5 6.4 8.9 10.2
RFV
Seeding rate effects on NDF, and RFV
Seeding Rate (million ha-1) NDF (%) RFV
1.5 43.3 b 148.5 a2.2 44.0 ab 144.4 b3.0 44.4 a 142.6 b3.7 44.7 a 143.6 b
Dual-use management and variety trials underway - 2020
Testing warm- and cool-season legume forage and cover crops in wheat-cotton rotations.
Cover Crop Trials – Mereta, TX
Red Clover
Crimson Clover
Hairy Vetch
Silver River Sweetclover
Winter peas
Pea Nodules
Active N-fixing!
